Policy management in a roaming or handover scenario in an IP network

ABSTRACT

The invention comprises methods and arrangements for Policy Decision Point discovery in a roaming or handover scenario in an IP network (IN) comprising a plurality of network elements. The invention comprises methods and arrangement in an user equipment for receiving the address of the serving policy decision point and sending to the Home Agent a registration request comprising the local IP address of the user equipment so that the home agent can register the local IP address. The registration request will also comprise the address (ASPDP1) of the serving policy decision point (SPDP1) so that the Home Agent can forward the address of the serving policy decision point to the anchor Policy Decision Point and so that the anchor Policy Decision Point can contact the serving policy decision point by using said address of the serving Policy Decision Point.

TECHNICAL FIELD

The present invention relates to policy management in an IP network. Inmore detail it relates to policy management in the case of roaming andhandover between two Policy Enforcement Points controlled by twodifferent Policy Decision Points.

BACKGROUND

Policy management in an IP network is an important function as thepolicies indicate essential conditions for the users in the network.

An example of an IP network is IP Multimedia Subsystem (IMS). IMS hasbeen developed by the 3^(rd) Generation Partnership Project (3GPP) as anopen standard, to give operators of access networks the ability to offermultimedia services in the packet domain. An IMS network can be builtabove any type of access network and is more or less independent of theaccess technology used. By using IMS, telecommunications operators canprovide services to users irrespective of their location, accesstechnology, and terminal. It also includes a handover of calls betweenfixed-line and mobile networks.

An important function of IP networks is the enforcement of differentpolicies. These policies dictate e.g. what particular users may and maynot do, what they will be charged or what Quality of Service (QoS) aparticular user will receive for a specific service. Policies areenforced using policy “rules”. A single policy may require a set ofpolicy rules. Policy rules are installed into a node through which alltraffic of the users pass or into multiple nodes, which collectivelyhandle all traffic of the user. Common functions in a policy managementsystem are a Policy Enforcement Point (PEP), a Policy Decision Point(PDP) and a subscriber database comprising subscriber/subscriptionrelated information.

In 3GPP the PDP functions are handled by the Policy and charging RulesFunction (PCRF), the PEP functions are handled by the PCEF located inthe GGSN and the subscriber database functions are handled by theSubscription Profile Repository (SPR).

For large IP networks it is common to have several PEPs and severalPDPs. Each operator has normally at least one subscriber database fortheir users. An important function in a case of an IP network is thepossibility of roaming and handover between different access points andaccess networks. Roaming occurs when a user of one service provider oroperator uses the facilities of another service provider or operator.Handover normally means the transfer of an ongoing call or data sessionfrom one channel connected to the network to another.

From a policy management point of view a Mobile Terminal access the IPnetwork via a PEP which is associated to a specific PDP, which controlsthe PEP.

For e.g. reasons of scalability, each operator could have several PDP inhis network. It is also possible that an operator has a specific PDP fora certain access, e.g. one PDP for 3GPP access and another one for WiMAxaccess. If a visited network or a home network comprises several PDPsthere is no solution today that can handle the policy management inroaming and handover between different PEPs.

In 3GPP R7 a mobile terminal accesses the IP network via a PCEF, a PEP,and the IP address of the subscriber will be associated to a PCRF, aPDP, which controls to the PCEF. If the IP Connectivity Access Network(IP-CAN) is GPRS the appropriate PCRF could be contacted based on whichAccess Point Name (APN) the mobile terminal is connected to. It is alsopossible to use the IP address to choose the appropriate PCRF.

For other IP-CANs the Gateway shall contact the appropriate PCRF basedon the access point the mobile terminal is connected to and, optionally,a mobile terminal identity information that is applicable for thatIP-CAN. In the case of GPRS the mapping from a certain user equipmentidentity and/or access point name to the PCRF is typically stored inpre-configured tables in the GGSN, the PCEF and the AF.

If there is a plurality of PCRFs in a network the policy management willnot work properly. If the mobile terminal has the possibility to accessthe network via different access points and access networks controlledby different PDPs, different nodes associated to the mobile terminaldoes not know which PDP that controls the policy management of a mobileterminal.

Other architectures have similar functions as the PCRF, e.g. TISPAN,WiMax Forum, DSL Forum and PacketCable. They also have similar solutionsto associate an end-user to a specific PDP.

SUMMARY

To make it possible for the policy management to work in an IP networkcomprising a plurality of Policy Decision Points (PDP) the network needsto set up connection between some of the policy management functions.

A method and arrangement in an user equipment for Policy Decision Pointdiscovery in a roaming or handover scenario in an IP network (IN). TheIP network comprises a user equipment (UE) assigned a local IP addressand an home IP address, a plurality of Policy Enforcement Points (APEP,SPEP1, SPEP2) including a serving Policy Enforcement Point (SPEP1)associated to the user equipment, a plurality of Policy Decision Points(APDP, SPDP1, SPDP2) including a serving Policy Decision Point (SPDP1)associated to the user equipment and the serving Policy EnforcementPoint (SPEP1), and an anchor Policy Decision Point associated to theuser equipment. The anchor Policy Decision Point has access to bothPolicy Rules and a subscriber database (120) comprising policyinformation related to the user equipment. The network also comprises anHome Agent (HA) associated to the user equipment.

The invention comprises methods and arrangement in an user equipment forreceiving the address of the serving policy decision point and sendingto the Home Agent a registration request comprising the local IP addressof the user equipment so that the home agent can register the local IPaddress. The registration request will also comprise the address(ASPDP1) of the serving policy decision point (SPDP1) so that the HomeAgent can forward the address of the serving policy decision point tothe anchor Policy Decision Point and so that the anchor Policy DecisionPoint can contact the serving policy decision point by using saidaddress of the serving Policy Decision Point.

An advantage with this invention is that it makes it possible to supporthandover and roaming scenarios between Policy Enforcement Points in anetwork comprising a plurality of Policy Decision Points.

The invention will now be described more in detail with the aid ofpreferred embodiments in connection with the enclosed drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram to illustrate one embodiment of the inventionin a roaming scenario.

FIG. 2 is a block diagram to illustrate one embodiment of the inventionin a handover scenario.

FIG. 3 is a block diagram to illustrate one embodiment of an userequipment.

DETAILED DESCRIPTION

FIG. 1 illustrates an IP network IN comprising a User Equipment UE, asubscriber database 120 comprising policy related subscriber data 121,policy rules PR, an Anchor Policy Decision Point APDP, Serving PolicyDecision Points SPDP1, SPDP2, an Anchor Policy Enforcement Point APEP,Serving Policy Enforcement Points SPEP1, SPEP2, an application functionAF, an AAA server AAA, an AAA proxy 131 and a Home Agent HA. The addressof the Serving Policy Decision Point SPDP1 is ASPDP1. A user equipmentUE is attached to the network. The AAA server can be integrated with theHSS server.

A Policy Enforcement Point (PEP) is a function that requests for accessto a resource or execution of a service. The PEP requests evaluation ofthese access/service execution requests to a Policy Decision Point(PDP). The PDP returns its decision to the PEP and the PEPenforces/carries out the decision that is returned by the PDP. The PEPcould e.g. block certain types of traffic according to the decision ofthe PDP or grant access to specific services.

The main task of a Policy Decision Point (PDP) is to evaluate requestsaddressed to the PEP. It evaluates the request against a policy. Theoutcome of the policy evaluation is the ‘decision’ of the PDP. The PDPand the PEP may be implemented as two distinct entities thatintercommunicate by means of a protocol.

An example of a PEP and the PDP is the Policy and Charging RulesEnforcement Function (PCEF) and the Policy and Charging Rules Function(PCRF) in 3GPP PCC R7. Critical traffic, e.g. voice, will be controlledby the PCRF.

An Anchor PDP controls the PEP from a policy management point of viewand has access to Policy Rules PR and specific policy information forthe Mobile Terminal, the Policy related Subscriber Data 121. A ServingPDP is the one that controls the PEP that the mobile terminal isconnected to. These PDPs could be situated everywhere in the network,e.g. in the access network, core network or service network.

The Policy Rules could be stored everywhere, e.g. in the different PDPsor in a separate policy database. In this particular embodiment they arestored in the Anchor PDP.

Policy related subscriber data 121, e.g. subscriber class or subscriberservices, for a particular user/subscriber 110 are stored in thesubscriber database 120. The subscriber database is normally located inthe Home network H. Protocol used between the subscriber database and aPDP could be e.g. LDAP. An example of a subscriber database is theSubscription Profile Repository in 3GPP R7.

The Application Function AF is an element offering applications thatrequire the control of IP bearer resources. The Application Function iscapable of communicating with the PDP to transfer dynamic serviceinformation, which can then be used for selecting the appropriatecharging rule and service based local policy by the PDP. One example ofan Application Function is the P-CSCF of the IM CN subsystem.

The home agent HA keeps among other things information about LO thecurrent IP address of the user equipment. A mobile user equipment thatattaches to the network will be assigned a local IP address. Thisaddress will be registered at the home agent. In MIPv6 this is done inthe message binding update from the user equipment to the home agent. InMIPv4 the corresponding message is called registration request.

The AAA function refers to protocols and supporting infrastructure forauthentication, authorization and accounting (AAA) in IP networks. Thepurpose of AAA is to verify the identity of the user (authentication),to verify what types of service the user is entitled to (authorization)and to collect data necessary for billing the user for the service(accounting).

If a mobile user accesses the network via another PEP than the AnchorPEP, e.g. a Serving PEP, SPEP1 in a visiting network, the user is goingto be associated to Serving PDP SPDP1, that controls the SPEP1. In thisexample he attaches to SPEP1 and the SPDP1 assigned.

To be able to enforce the proper policy decisions the SPDP1 and the APDPmust communicate with each other. Preferably the APDP discover the SPDP1and initiate the PDP-PDP interaction. This could be done via theinterface S9 mentioned in 3GPP TS 23.203 and TR 23.882. To be able toset up a connection the invention proposes that one of the PolicyDecision Points, SPDP1 or APDP, receives the address of the other one.To be able to do this, the invention introduces a method to deliver theaddress (ASPDP1) of the serving policy decision point to the anchorpolicy decision point. The method comprises the feature of includingthis address in the communication in the IP mobility procedure of theuser equipment.

A first embodiment describes a roaming scenario according to FIG. 1. Ina first embodiment the Anchor PDP is situated in the Home operatornetwork H and the Serving PDP, SPDP1, is situated in a visited networkV. The Anchor PDP is also connected to an Application Function (AF)situated in the Home network H. The home agent HA is situated in thehome network H and the user equipment is connecting to a PolicyEnforcement Point, SPEP1, in the visiting network V. An AAA server isintegrated with the HSS server. There is an AAA proxy in the visitednetwork. The method comprises the following steps.

-   -   The user equipment UE attaches to the visited network.    -   Run an access authentication procedure.    -   Assign an home agent(HA)    -   Run DHCP discovery for assignment of the local IP address to the        UE.    -   Configure the UE with the address (ASPDP1) of the SPDP depending        on the assigned IP address.    -   IP session request is send to S-PDP    -   Run IP security between UE and the AAA server, via the AAA        proxy, assign an home agent PoP (HA) and include the HA in the        successful response of the IP security.    -   HA assigns a home IP-address of the UE and an anchor policy        decision point APDP.    -   APEP, including the HA, sends IP session setup to the APDP.    -   UE starts MIP binding update or registration request to the HA        including the S-PDP address.    -   HA sends update request to A-PDP including the S-PDP address.    -   The APDP creates a default PCC rule after interaction with the        subscriber database 120, initiates a PDP-PDP interface to push        rules to the SPDP1.    -   The SPDP1 push rules after possible modification to the SPEP1.        The session ID can be used to bind local IP address and the home        IP address in APDP.

The nodes and functions can be situated in all kind of constellationsconcerning the home network and the visited network. In e.g. a handoverscenario, all the nodes and functions will be situated in the homenetwork. In the handover case there is no need for an AAA proxy 131.

A second embodiment describes a handover scenario according to FIG. 2.Both the Anchor PDP, APDP, and the Serving PDP, SPDP1, is situated in ahome network H. The Anchor PDP is also connected to an ApplicationFunction (AF) situated in the Home network H. The home agent HA issituated in the home network H and the user equipment is connecting to aPolicy Enforcement Point, SPEP1 also situated in the home network. Thereis no AAA proxy needed in this case. The method comprises the followingsteps.

-   -   The user equipment UE attaches to a new access in the home        network.    -   Run an access authentication procedure.    -   Assign an home agent(HA)    -   Run DHCP discovery for assignment of the local IP address to the        UE.    -   Configure the UE with the address (ASPDP1) of the SPDP depending        on the assigned IP address.    -   IP session request is send to S-PDP    -   Run IP security between UE and the AAA server, assign an home        agent PoP (HA) and include the HA in the successful response of        the IP security.    -   HA assigns a home IP-address of the UE and an anchor policy        decision point APDP.    -   APEP, including the HA, sends IP session setup to the APDP.    -   UE starts MIP binding update or registration request to the HA        including the S-PDP address.    -   HA sends update request to A-PDP including the S-PDP address.    -   The APDP creates a default PCC rule after interaction with the        subscriber database 120, initiates a PDP-PDP interface to push        rules to the SPDP1.    -   The SPDP1 push rules after possible modification to the SPEP1.        The session ID can be used to bind local IP address and the home        IP address in APDP

FIG. 3 illustrates an user equipment (UE) used in the methods describedabove. It comprises means 330 for receiving the address ASPDP1 of theserving Policy Decision Point SPDP1 associated to the user equipment UE,means 340 for storing an address ASPDP1 of the serving Policy DecisionPoint and means 350 for sending the address of the serving policyDecision Point to the Home Agent so that the Home Agent can forward theaddress of the serving policy decision point to the anchor PolicyDecision Point.

The invention claimed is:
 1. A method in a user equipment, suitable forPolicy Decision Point discovery in a roaming or handover scenario in anIP network (IN), the method comprising: receiving at a user equipment anaddress of a serving Policy Decision Point; sending to a Home Agent aregistration request comprising a local IP address of the user equipmentso that the home agent can register the local IP address of the userequipment, the registration request comprising the address of theserving Policy Decision Point, and wherein the registration request is arequest message according to MIPv4 standard or a binding update messageaccording to MIPv6 standard; forwarding the address of the servingPolicy Decision Point from the Home Agent to an anchor Policy DecisionPoint, wherein said anchor Policy Decision Point has access to policyrules and a subscriber database comprising policy information related tothe user equipment; and the anchor Policy Decision Point contacting theserving Policy Decision Point by using said address of the servingPolicy Decision Point; wherein the IP network comprises a plurality ofPolicy Enforcement Points, including the serving Policy EnforcementPoint associated with the user equipment; and wherein the IP networkfurther comprises a plurality of Policy Decision Points including theserving Policy Decision Point associated with the user equipment and theserving Policy Enforcement Point.
 2. A user equipment connectable to anIP network (IN), which is assigned a local IP address and a home IPaddress, the user equipment is associated to a home agent (HA), to aserving Policy Decision Point and to an anchor Policy Decision Point,where said anchor Policy Decision Point has access to both Policy Rulesand a subscriber database comprising policy information related to theuser equipment, the user equipment comprising: means for receiving theaddress of the serving Policy Decision Point; means for storing addressof the serving Policy Decision Point, means for sending to the HomeAgent a registration request comprising the local IP address of the userequipment so that the home agent can register the local IP address ofthe user equipment characterized in that the registration requestcomprises the address of the serving Policy Decision Point associated tothe user, and where the registration request is a request messageaccording to MIPv4 standard or a binding update message according toMIPv6 standard, wherein the Home Agent forwards the address of theserving Policy Decision Point to the anchor Policy Decision Point,wherein said anchor Policy Decision Point has access to policy rules anda subscriber database comprising policy information related to the userequipment: and wherein the anchor Policy Decision Point contacts theserving Policy Decision Point by using said address of the servingPolicy Decision Point; wherein the IP network comprises a plurality ofPolicy Enforcement Points, including the serving Policy EnforcementPoint associated with the user equipment; and wherein the IP networkfurther comprises a plurality of Policy Decision Points including theserving Policy Decision Point associated with the user equipment and theserving Policy Enforcement Point.